Various wireless access systems such as cellular phone, wireless LAN, and PHS have spread and a wireless MAN service such as WiMAX (Worldwide Interoperability for Microwave Access) is going to start.
In order to effectively use such an access system, research and development on a technology to make handover to a different type of wireless network in a seamless way has progressed (See Non-Patent Documents 1 and 2).
Also, as disclosed in Non-patent Document 3, a software radio technology to enable connection to a different wireless interface in order to switch a different wireless system has been studied.
On the basis of these technologies, limited wireless resources (frequency, wireless infrastructure) and network resources can be efficiently utilized by switching to an optimal one according to the situation of the wireless network. Also, as a result, throughput or capacity in total can be improved, and use efficiency of the frequency is improved.
On the other hand, since mobile communication terminals such as PDA, cellular phone, and small-sized laptop computer are provided with a plurality of wireless communication methods, a user can select and switches to an optimal one from those methods or use some at the same time so as to increase the communication speed and to conduct wireless communication.
However, different data communication devices should be used actually according to the method or wireless network operator in many cases.
For example, suppose such a case that one wireless network operator provides a data communication device of a USB interface, while another wireless network operator provides a data communication device of a PCMCI interface.
As the result of progress of the software wireless technology, it is technically possible to use only a single data communication device while switching is made to a plurality of communication methods, but it is not considered to have spread among general users.
Also, it is technically possible to make connection to a plurality of wireless network operators with a single data communication device, but each wireless network operator provides their exclusive data communication device in many cases. Therefore, it becomes necessary to connect a plurality of data communication devices to a communication terminal in general.
At this time, if there are many wireless network operators and communications methods to be used and the number of required data communication devices is large, data communication ports of the communication terminal are all used up and other devices cannot be connected to the terminal or there might be a case in which even the data communication ports are not sufficient for all the devices to be connected in the first place.
Also, the mobile communication terminal is designed suitable for portability, but connection with the data communication devices increases the volume or causes protrusions, which damages portability of the mobile communication terminal.
Moreover, since the data communication device usually executes processing such as flow control or error correction in addition to wireless transmission/receiving, the device holds a larger proportion in power consumption as compared with the main body of the mobile terminal or the other devices connected to that in many cases, and there is a problem that a battery operating time, which is important for the mobile terminal, is reduced.
Non-Patent Document 4 introduces a device called personal media gateway. Using this, a function to communicate with a base station can be separated from the mobile terminal, and the device functions as an access point to a plurality of the mobile terminals. However, incorporation of functions such as selection of the above-mentioned data communication device, connection, disconnection, aggregation of bands, discrimination and sorting of communication contents and the like is not assumed, and the device merely performs relaying of data communication.
Technologies relating to the present invention have been examined by the applicants of the present application as a technology relating to collection of wireless information. For example, Non-Patent Document 5 as a technology for a terminal to autonomously recognize a usable network, Non-Patent Document 6 as a technology to obtain the respective network QoS information on a real-time basis, and Non-Patent Document 7 as a technology to make efficient wireless resource reservation for seamless handover which can handle high-speed movement are disclosed, respectively.
Related Patent Documents include Patent Document 1 which discloses a software wireless communication device. This software wireless communication device can handle a plurality of frequencies or wireless methods by switching software since a received radio wave is along-digital converted by an AD converter once, and demodulation or the like is performed by a digital signal processor or micro processor and software.
Also, Patent Document 2 discloses a cognitive communication system in which a database device holding information on a use state of wireless channels is connected to each base station provided in the respective wireless access networks and the database device having a database of frequencies used by an existing wireless access network for integrating the database device into each base station side is installed.
In order to manage wireless access devices with different communication methods or management methods in an integrated manner, standardized functions and a communication interface between different devices are required. However, such a function is realized in the prior art by devices developed specially for the wireless system, in which functions in the devices are different and moreover, an interface between the devices is not standardized, and there is a problem that a general-purpose device cannot be developed.
Patent Document 3 discloses an integrated relay system in which plural pieces of relay system monitoring information can be managed by a single parent station device of the relay system in an integrated manner. This relay system performs relaying between a base station and a portable terminal in a wireless communication system, but this is a system for relaying in a radio-wave dead zone such as a tunnel and not for using plural types of wireless communication systems by dynamically reconfiguring them.
Non-Patent Document 1: G. Wu, P. Havinga and M. Mizuno, “MIRAI Architecture for Heterogeneous Networks,” IEEE Comm. Mag., pp. 126-134, 2002
Non-Patent Document 2: M. Inoue, K. Mahmud, H. Murakami, M. Hasegawa and H. Morikawa, “Novel Out-Of-Band Signaling for Seamless Interworking between Heterogeneous Networks,” IEEE Wireless Commun., Vol. 11, No. 2, pp. 56-63, 2004
Non-Patent Document 3: H. Harada, “Software defined radio prototype toward Cognitive Radio Communication Systems,” IEEE Dyspan 2005, Vol. 1, pp. 539-547, 2005
Non-Patent Document 4: “Internet Magazine”, Impress R&D, pp. 86-89, February, 2006, http://i.impressrd.jp/files/images/bn/pdf/im200602-085-strategy.pdf
Non-Patent Document 5: Go Miyamoto, Kentaro Ishizu, Mikio Hasegawa, Yoshitoshi Murata, “Cognitive Wireless Cloud (2)˜Data Collection Method for Finding Wireless Resources” IEICE Technical Report, Technical Committee on Software Radio, March 2007
Non-Patent Document 6: Yoshia Saito, Mikio Hasegawa, Yoshitoshi Murata, “Cognitive Wireless Cloud (3)˜High-speed End-To-End QoS Measuring Method” IEICE Technical Report, Technical Committee on Software Radio, March 2007
Non-Patent Document 7: H. N. Tran, M. Hasegawa, Y. Murata, “Resource Reservation Scheme for Mobile Users in Cognitive Wireless Cloud” IEICE Technical Report, Technical Committee on Software Radio, March 2007
Patent Document 1: Japanese Patent Laid-Open No. 2003-152732
Patent Document 2: Japanese Patent Laid-Open No. 2007-184850
Patent Document 3: Japanese Patent Laid-Open No. 2006-128980